Does onion powder go bad? Shelf life, caking and 6 brands

Onion powder fades rather than spoils. Makers date it with a best-by code, and Simply Organic puts herbs and spices in general at 2 to 3 years stored properly. When it sets into a lump, look at moisture first: McCormick says onion powder pulls water from the air and names a common way in, shaking the jar over a steaming pot.

A customer asked McCormick why the jar turned into “an unusable rock” within weeks. Its reply was that “Products containing onion and garlic ingredients are particularly susceptible to caking because these are hygroscopic”, meaning they pull moisture from the air. It advises keeping the jar in a dry, cool cupboard rather than over the sink or the range, keeping it tightly sealed, and not sprinkling or grinding straight into a steaming pot, because that lets moisture into the container. So the jar that sits next to the stove and gets shaken over the soup every night is set up to fail, whatever the date on the lid says. A wetter condiment is a different story, which is why our guide to how long vegan mayo keeps reads nothing like this one.

How long does onion powder last?

The makers do not agree, and one of them does not agree with itself. McCormick’s guide says that, generally speaking, dried seasonings, herbs and spices in jars last about 1 to 2 years, then lists ground spices at 2 to 4 years a few lines further down. Simply Organic says 2 to 3 years for herbs and spices in general. Frontier Co-op splits ground herbs and spices by plant part: leaves 2 to 3 years, seeds and barks 1 year, roots 2 years. An onion is a bulb, which is on none of those lines.

The practical answer is the date the maker printed. McCormick puts its best-by date on top of the lid; Simply Organic prints “Best By” on the bottom of the bottle; Frontier prints a best-by date on every bottled spice. McCormick also suggests writing the opening date on a new jar with a permanent marker.

That date is about flavor, not safety. The USDA’s food safety service defines “Best if Used By” as the date a product will be at its best flavor or quality, and says it is not a purchase or safety date. Simply Organic’s test for a tired spice is to crush a little in your palm: if the aroma does not hit you straight away, the flavor has faded too. Clumping or an unusually dry feel can mean moisture or age has got to it. Mold is a different matter, and Frontier names where it comes from: temperature swings cause condensation, and condensation eventually causes mold.

Should onion powder go in the fridge?

Usually no. Frontier’s ideal is a fairly constant temperature below 70°F, away from the stove, the furnace and the sun, in airtight containers kept dry and dark. A fridge is cold enough, but every trip out to the counter and back is the temperature swing Frontier warns about, and Frontier says that if you do keep spices in the fridge or freezer, you should put them back promptly after use. For a powder that pulls water out of the air, a cool cupboard away from the stove is the simpler answer.

Six onion powders, label by label

We read each maker’s own product page in October 2026. Four list nothing but onion, and Frontier says its powder has no additives, which makes those five vegan by the makers’ own descriptions; none carries a vegan claim, and none needs one. Prices are the makers’ own store prices on the day we read them, and every per-ounce figure is our arithmetic.

Lawry’s Onion Powder

Our pick for most kitchens. The ingredient list reads “onion powder” and nothing else, and McCormick’s store sells the 2.62 oz jar for $3.99, about $1.52 per ounce. That is the lowest per-ounce price of the small jars here. Skip it if you want organic: nothing on the page claims it.

McCormick Onion Powder

Same size as the Lawry’s jar, same store, same one-word ingredient list (“Onion Powder”), and $5.49, about $2.10 per ounce. What you get for the extra $1.50 is the most useful product page of the six: the caking advice above, a confirmation that it contains no gluten, and a statement that it is made in the USA. If the Lawry’s jar is on the same shelf, there is nothing on either page that justifies paying more.

Simply Organic Onion Powder

“Organic Onion.” is the whole list, and the maker describes it as U.S.-grown onions with no additives. The 3.00 oz jar is $7.19, about $2.40 per ounce, the highest of the five onion-only powders here. It is the one to buy if you want organic in a jar and use onion powder slowly; the best-by code on the bottom of the bottle tells you when to stop expecting full flavor. If you go through onion powder fast, the Frontier bag below is about a third cheaper per ounce (our arithmetic).

Frontier Co-op Organic Onion Powder

Frontier says this one is made from onions dried and ground with no additives or chemicals, and the 6.14 oz pack costs $9.59, about $1.56 per ounce for organic. The page says its stand-up bags are made to keep products “as fresh on the last day as they are on the first”. Frontier’s own storage guide says all herbs and spices age, even under the best conditions, which is the more honest of the two sentences. Do not buy the bag if your kitchen is humid and you scoop with a wet spoon.

Watkins Organic Onion Powder

The list reads “Organic Onion”, and Watkins sells it in three sizes on its own store: 2.8 oz for $5.99, 8.3 oz for $10.49 and 22 oz for $14.49. That is about $2.14, $1.26 and $0.66 per ounce, so the 22 oz size is the cheapest onion powder per ounce we found. It is also a lot of powder to keep dry once it is open. Buy it only if you cook for a crowd or run a kitchen; for everyone else, the 8.3 oz size is the organic bargain here.

Morton & Bassett Onion Powder

The 2.3 oz jar is $9.49, about $4.13 per ounce, the most expensive of the six by a distance. Its page gives a conversion, half a teaspoon for one small onion, but no ingredient list, so we cannot tell you what is in it beyond the name. Spice Islands, which also gives no list on its page, uses a different yardstick, 1 tsp of powder for 3 tbsp of freshly minced onion. Don’t pay the most per ounce for the jar that tells you the least.

Whichever jar you buy, keep it closed, keep it out of the steam and check the date on the lid or the base before you blame the recipe. If you are still deciding between the powder and a fresh onion, the swap ratios are in our guide to whether onion powder is the same as onion.